The present invention is related to blanket hooking means for use with a blanket cylinder for holding a blanket around the cylinder in order to secure the blanket thereon. More particularly, the invention is directed to a blanket hooking means which is easy to attach to a blanket cylinder and which facilitates rapid attachment of the blanket to the blanket cylinder with a minimum of effort and requiring little experience and time.
Blanket hooking or clamping means known in the prior art are shown, for example, by the patent to Kneppler, U.S. Pat. No. 838,790, issued Dec. 18, 1906 and by the patent to Graves, U.S. Pat. No. 3,062,141, issued Nov. 6, 1962. The apparatus shown in each of these patents illustrate one type of prior art blanket cylinder which includes an axially extending cylinder opening which houses the means for hooking or clamping the blanket. These prior art blanket cylinders illustrate a well known method of supporting a hooking means wherein a pair of axially extending rods which are an integral part of the blanket cylinder are employed as a means for supporting the blanket hooking mechanisms. The presence of the supporting rods in blanket cylinders of this type facilitates the use of blanket hooking means which provide a relatively satisfactory blanket hooking mechanism.
The other type of blanket cylinder which is generally used, however, is provided with a cylinder opening generally narrower than those of the first type and does not include the pair of axially extending rods. Heretofore, there has been no satisfactory hooking means provided for use with this second type of blanket cylinder. Generally these blanket cylinders employ a blanket clamping means which includes a pair of elongated clamps which are secured to the floor of the cylinder opening. The clamps each comprise a pair of elongated jaws which are held together in clamping relationship by a large number of screws. Insertion or removal of the blanket using such clamps is time consuming because all of the screws on both pairs of jaws must be removed or tightened. Clamping means of this type also have the additional disadvantage that the screw heads include hexagonal bores for receiving an allen wrench or the like and these bores collect ink residue which becomes crusted. It is thus frequently difficult to insert a wrench into the hexagonal bores to permit adjustment of the screws. Furthermore, it is not uncommon for screws used in such clamping means to work loose and to cause scoring or other damage to opposing cylinders of the printing press. A fundamental property of blankets which are generally used on the blanket cylinder is that they are generally resilient and stretch after continued use. Consequently, it was necessary with the prior art to frequently adjust the clamping means to compensate for the stretch of the blanket.
Generally it is not feasible to modify the cylinders of the second type to incorporate the blanket clamping means of the type shown in Kneppler or Graves primarily because the cylinder opening is too narrow and too shallow. Secondly, the addition of the rods to the cylinder would require disassembly of the blanket cylinder as well as costly machining.